Although operation microscopes used in performing microsurgical techniques have been provided with illumination devices, those utilized heretofore are not satisfactory for many procedures. Specifically, widely used microscopes such as the Zeiss Opmi 1 may be provided with 30 watt or 50 watt filament lamps mounted in a lamp housing assembly. However, a major, if not critical disadvantage with such illumination systems is their failure to provide sufficient light for deep cavity surgery. Sufficient illumination is especially important in chest, back or abdominal surgery, which, due to the nature of the incision, requires significant light. For example, in deep disc surgery, conducted through a one inch long incision which is nominally four inches deep, the dark muscle walls absorb much light, and the shadows may substantially mask or otherwise hinder clear observation of the desired operative area.
Another important adjunct to microscopic surgery is the desirability to photograph, and especially record on motion picture film, video tape or televise the procedure. Although a 50 watt lamp is provided with a high intensity power source adapter, it is found that the lamp usually is burned out after less than two minutes of such high intensity use. Obviously, to interrupt the procedure in order to change a lamp because of failure is most unfortunate and undesirable.
Another significant disadvantage of microscope illumination systems known heretofore utilizing tungsten filament lamps is slow dissipation of heat. Especially problematic is the hot lamp housing which will cause burning, melting or fusion of a drape normally used over the surgical area in order to maintain sterility and prevent contamination of the field. However, when the drape comes in contact with the hot lamp housing, burning of the drape is obviously most unfortunate, not only from loss of field sterility because of exposure to the ambient surroundings when the drape integrity is interrupted, but danger of fire, noxious fumes from melting plastic, and even injury to the patient or surgeon from molten or burning drape material are of concern. In order to reduce or eliminate such heat problems, there are fiber optic illumination systems for operation microscopes. Although they provide a cool light source thereby obviating the problems previously described, the very nature of a fiber optic system results in significant lamp intensity loss between the 150 watt halogen bulb normally used. Not only is low intensity a problem but the resulting color spectrum from the lamp is unsuitable for use with easily available film such as high speed Ektrachrome 150, for recording the procedure. In other words, color distortion from the fiber optics does not yield desirable or acceptable film reproductions of the operation, let alone, sufficient light for color filming, televising or video tape recording.